Sink strainer



FIG. 1 is a perspective view of a sink strainer showing our design;

FIG. 2 is a front elevation view;

FIG. 3 is a rear elevation view;

FIG. 4 is a side elevation view;

FIG. 5 is a top plan view; and,

FIG. 6 is a bottom plan view. 

CLAIM The ornamental design for a sink strainer, as shown and described. 